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ESSENTIALS OF DIAGNOSIS

Central nervous system (CNS) vasculitis comprises a host of different underlying diseases that can cause inflammatory damage of blood vessels in the brain and spinal cord. About half of the cases have no known cause and no other systemic manifestations and are therefore classified as primary vasculitis of the CNS. The other half of the cases arise in the setting of an underlying disorder, often a systemic rheumatologic disease or (less commonly) an infection. Those cases are classified as secondary forms of CNS vasculitis. Primary vasculitis of the CNS, the focus of this chapter, has been referred to by many names, leading to sometimes confusing terminology. We will use the term “primary angiitis of the CNS” (PACNS) in this chapter.

It is important to recognize and treat the rare patients whose strokes and other neurologic deficits result from PACNS. However, it is also important for clinicians to avoid overdiagnosis of PACNS, because the angiographic and magnetic resonance imaging (MRI) abnormalities observed in this condition can be mimicked closely by infection, noninflammatory vasculopathy, malignancy, and other conditions.

  • Common findings at presentation include headache, encephalopathy, and multifocal strokes.

  • The differential diagnosis of PACNS encompasses systemic inflammatory, infectious, and malignant etiologies, as well as reversible cerebral vasoconstriction syndrome (RCVS).

  • Angiographic abnormalities may be highly consistent with PACNS but are never diagnostic in and of themselves, and can be seen in one (or more than one) of its potential mimickers. Similarly, high-resolution MRI with vessel wall imaging can help to differentiate vasculitis from atherosclerosis but the specificity of such findings remains imperfect and always requires careful clinicoradiologic correlation.

  • Definitive diagnosis requires brain biopsy to confirm histopathologic vasculitis. Even with biopsy findings, however, clinicopathologic correlation is required to confirm the diagnosis of PACNS.

General Considerations

PACNS is a disease of unknown cause characterized by vasculitis limited to the brain and spinal cord. PACNS is a rare disease. At large medical centers, PACNS constitutes only about 1% of all cases of systemic vasculitis. The annual incidence is 2.4 cases per 1,000,000 person-years.

CLINICAL FINDINGS

A. Symptoms and Signs

The average age of onset is around 50 years but patients of any age, including children, can be affected. The initial presentation commonly involves headache, cognitive changes, focal neurologic changes such as hemiparesis, or other persistent neurologic deficits. Less commonly, seizures or vision changes are part of the presentation. A summary of the clinical signs and symptoms seen at presentation is shown in Table 36–1.

Table 36–1.Clinical and laboratory features of PACNS at the time of presentation

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